The Primary Breast Cancer Therapy Group (NSABP) is a multidisciplinary cooperative group consisting of surgeons, pathologists, medical oncologists, radiation therapists, and more recently nurse oncologists who have been added to the group. Patients entered into earlier protocols are being followed. We are participating in two ongoing protocols and are preparing to enter two new protocols for: (1) Stage I breast cancer. (2) Stage III breast cancer. This institution has participated since the start of Group activities in 1958. The grant application is being submitted for support of our institution's participation in the protocols conducted by the Headquarters grant application submitted by the Project Chairman, Dr. B. Fishero Einstein's Project Director is a member of the Protocol Design Committee. In addition to participating in protocol studies we are providing the Headquarters Office with samples of breast tumors for estrogen more recently progesterone protein binding receptor studies.